package lesson6;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;

public class UdpSever {
    DatagramSocket socket = null;
    public UdpSever(int port) throws SocketException {
        socket = new DatagramSocket(port);
    }

    public void start() throws IOException {
        //1 启动服务器
        System.out.println("服务器启动");
        while(true){
            //2 构造Pacet接受请求
            DatagramPacket requestPacket = new DatagramPacket(new byte[4096], 4096);
            socket.receive(requestPacket);
            //3 根据请求返回响应
            String request = new String(requestPacket.getData(), 0, requestPacket.getLength());
            String response = process(request);
            //4 发送响应
            DatagramPacket responsePacket = new DatagramPacket(response.getBytes(), response.getBytes().length,
                    requestPacket.getSocketAddress());
            socket.send(requestPacket);
            //5 打印日志
            System.out.printf("[%s:%d] req: %s, resp: %s\n", requestPacket.getSocketAddress().toString(),
                    requestPacket.getPort(), request, response);
        }
    }
    public String process(String request){
        return request;
    }

    public static void main(String[] args) throws IOException {
        UdpSever sever = new UdpSever(9090);
        sever.start();
    }
}
